This invention relates to a rotating spray nozzle.
A vacuum toilet system for use on a passenger aircraft includes at least one sewage collection tank for receiving sewage (waste plus rinse liquid) during an aircraft flight. During servicing of the aircraft between flights, the collection tank is emptied, typically into a municipal sewage treatment system.
In a vacuum toilet system, the sewage collection tank has a sewage inlet connection that is connected through the aircraft sewer pipe to a discharge valve at the outlet of a toilet bowl, and an air outlet connection that is connected to a source of partial vacuum. When the discharge valve is opened, air rushes into the sewer pipe, entraining sewage present in the toilet bowl, and the sewage and transport air flow through the sewer pipe into the collection tank. The sewage is separated from the transport air in the tank and is retained in the tank, whereas the transport air leaves the tank by way of the air outlet connection and is exhausted from the tank to the exterior of the aircraft. Separation of the sewage and air may be accomplished by use of a cyclone device mounted at the sewage inlet connection of the collection tank. As a result of operation of the cyclone device, the sewage entering the tank is flung against the walls of the tank.
It is desirable that the interior surface of the collection tank be washed during servicing, in order to ensure that the tank is completely emptied and waste does not accumulate on the walls of the tank. It has been proposed that a spray nozzle should be mounted inside the tank and connected to a source of water under pressure for cleaning the tank. By this means, the area of the tank wall on which the jet from the spray nozzle impinges is effectively cleaned. If the spray nozzle is fixed, there are areas of the tank wall on which the jet does not impinge and are therefore not cleaned. Providing multiple nozzles to achieve better coverage increases the area of the tank wall that receives cleaning action, but the available cleaning energy is shared among the jets and therefore the effectiveness of each jet is less than that of the jet in an arrangement having a single cleaning jet.
It has been proposed that the spray nozzle should be mounted to rotate. If the spray nozzle rotates about a single axis, it sprays in a plane perpendicular to its axis of rotation and cannot provide cleaning action to the entire area of the tank wall. If multiple nozzles are spaced apart along the axis of rotation, they spray in respective planes spread out along the axis of rotation and cover a larger proportion of the area of the tank wall. Thus, as in the case of fixed nozzles, addition of nozzles improves coverage but reduces the energy in each jet so that each nozzle is less effective in cleaning and rinsing.
It has been estimated that an increase of one kilogram in the permanent flying mass of a passenger aircraft translates into an increase of about $45,000 to $90,000 in operating costs over the life of the aircraft. Accordingly, mass is an important consideration in design of components for use aboard passenger aircraft.